


I Know My Sister Like I Know My Own Mind

by daystarsearcher



Category: Doctor Who, Doctor Who (2005)
Genre: Character Study, F/F, Fluff, Romance, and thus begins the tradition of Kate/Osgood fics with Hamilton titles
Language: English
Status: Completed
Published: 2016-02-08
Updated: 2016-02-08
Packaged: 2018-05-19 04:08:48
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,844
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5953072
Author URL: https://archiveofourown.org/users/daystarsearcher/pseuds/daystarsearcher
Summary: <blockquote class="userstuff">
              <p>Osgood's newest sister has some definite opinions on this unresolved sexual tension business between Osgood and Kate, and is going to share them with Kate, whether Kate and Osgood like it or not.</p>
            </blockquote>





	I Know My Sister Like I Know My Own Mind

**Author's Note:**

> Doctor Who does not belong to me. Nor does Hamilton, the source of the title (I took a song lyric massively out of context).
> 
> I refer to Osgood's new sister as Petronella, because if that's the only punishment she's going to get for her previous actions, it will have to be enough.

“Oh my god, just take Osgood to a hotel and give her a spanking already,” Petronella said, throwing herself into the chair across from Kate’s desk and propping her boots up on said desk insouciantly.

It really was much easier, Kate reflected during the next two minutes while she was nearly choking to death on her coffee, to tell Osgood and her latest sister apart than it had been with her previous Zygon counterpart. Perhaps it was that they had not been linked as long, perhaps it was the lingering memory of previous links, perhaps they were simply more different individuals. Regardless, no matter the memories, enthusiasms, and fashion sense shared between them, Petronella had just a bit more confidence than Osgood, a bit sharper of an edge in her tone, a bit more of a mischievous glint in her eye.

Also, Petronella said things like, ‘Oh my god, just take Osgood to a hotel and give her a spanking already,’ while you could probably threaten Osgood with anything up to and including bamboo splinters under her fingernails and a permanent moriatorium on new Star Trek spin-offs before she would utter a sentence even remotely similar to that.

“Excuse me?” Kate managed as soon as she had managed to clear most of the coffee from her windpipe.

“She’s pining more than a forest in Norway,” Petronella complained with a pout that would have stopped Kate’s heart dead if it had appeared on Osgood’s face instead. “It’s the background radiation of every thought going through her head: ‘oh, Kate doesn’t want me, Kate never cared about me, Kate won’t ever let me touch her unless I tell her I’m a human which I can’t because I’m the peace and that has to be all that matters, Kate looks so fantastic in that suit and incidentally does she keep handcuffs in her bedside table drawer, I bet she does.’ It’s an endless loop.”

“There’s no way Osgood wants you to be saying all this to me,” Kate pointed out, her tone carefully even as she fought to keep down her heart rate. 

“Of course not,” Petronella agreed. “That’s why I had to do it spur of the moment, before she could stop me. She’s actually taking the stairs two at a time right now.” She gave a sympathetic wheeze. “She’d have got much better marks in P.E. if she’d shown half this speed.”

“Inhaler!” Kate said automatically.

Petronella pulled one out of her pocket and took a puff.

“Is Osgood doing that too?” Kate asked.

Petronella rolled her eyes. “Yes, Mum.”

“There are two people in this world who get to call me ‘Mum,’ and you are not one of them,” Kate said coldly. “Watch your tone.”

Petronella held up her hands in a placating gesture. “Seriously, though. She wants you. You want her. Hotels have room service. What am I missing here?”

Kate considered, for a moment, the many different denials she could give. She didn’t owe this woman anything. Bad enough that she was in Osgood’s head, she didn’t need to be privy to Kate’s thoughts too.

But Osgood might be listening through the link, and Osgood deserved the truth. 

“I don’t have sex for an audience,” she said stiffly.

To Kate’s great annoyance, Petronella’s only reaction to this admission was to make an affronted face. “What, you think I want to see you naked? I can barely stand humans when they’ve still got their clothes on. Trust me, I will not be looking.”

“You just complained about overhearing Osgood’s thoughts,” Kate pointed out, trying not grind her teeth. “You share her memories.”

“I exaggerated for dramatic effect!” Petronella said. “Like you’ve never done that during a negotiation.” She sized up Kate’s skeptical look and went on. “Look, do you know the Pythagorean theorem?” 

“Does the head of the Earth’s premier scientific organization know basic geometry?” Kate asked dryly. “Yes, actually.”

“But you’re not constantly thinking about it, are you?” Petronella pointed out. “You don’t go around with a never-ending loop of ‘a squared plus b squared plus c squared’ blaring in your brain. You have to pluck up a little file that says ‘Pythagorean theorem’ on it. Well, I don’t have to know what shenanigans you and Osgood are getting up to if I don’t go looking for that file. And believe me, I do not intend to go looking for that file. I will be locking that file in a file cabinet, hiding that cabinet behind a hideous rubber plant and a cubicle wall, and going to a budget meeting in an entirely different part of the building altogether. This metaphor is getting away from me.”

Kate felt a momentary soaring of hope within her heart before she forced herself to squash it.

“That would never work,” she said. “It’s like saying, ‘Don’t think about purple elephants.’ Once you do, you can’t think about anything but them.”

Petronella looked confused. “Why would you be thinking about purple elephants if you decided to stop thinking about them?”

There was a moment where they both looked at each other in bewilderment, before it clicked.

“This is a Zygon/human difference thing, isn’t it?” Kate asked. “You exercise more cognitive control—”

“Because otherwise the flow of input from an original would create complete sensory and cognitive chaos!” Petronella finished. “And humans don’t—I suppose I knew that intellectually, but I never really thought about it before.”

“Fascinating,” Kate said, and meant it.

Petronella grinned. “So see, there’s absolutely nothing stopping you from bending Osgood over a—”

“That is quite enough,” Kate said, her tone instantly switching from ‘interested scientist’ to ‘military commander.’ "Enlightening as this has been, I am done having this conversation with you.” She stood and stalked to the door, holding it open in a clear order to her subordinate. “If Osgood is interested in changing the status of our relationship, she can speak to me herself. And if you’re truly uninvested in the outcome, perhaps you could leave us to figure it out ourselves.”

“Speak of the devil,” Petronella said, standing with a lazy grin. She gave Kate a cheeky smirk and a little wave as she sauntered away past an out-of-breath Osgood, red-faced and with strands of hair sticking to her temples. 

“Inhaler,” Kate said, waving her into her office. “Sit down before you have a heart attack.”

Osgood sank into the chair her sister had just vacated. “I’m so sorry, ma’am—”

“Inhaler!” Kate repeated as she went to put on the electric kettle, and this time Osgood complied, taking a long puff and not saying another word until Kate brought her the mug of Darjeeling.

Osgood took a sip, her breathing much calmer but her face still twisted in distress as she gazed down into the liquid, not meeting Kate’s eyes. “I’m really very sorry,” she said quietly. “She gets—protective. I’ll speak to her. It won’t happen again.”

Kate perched on the edge of the desk next to her, pretended not to notice the way Osgood’s eyes flicked to her legs as she did so. “Not to worry. On the scale of damage she could do, this was slightly less than a terrorist attack.”

Osgood shot her a quick surprised look, and Kate raised an eyebrow. The Doctor might have kept Kate out of the negotiations during the latest close call with the treaty, but it hadn’t taken a genius to figure out where Osgood’s new sister had come from.

“You’re…all right with that?” Osgood asked.

“I trust your judgment,” Kate said simply.

Osgood looked up at her with wide eyes. “Thank you.”

Kate tried to ignore the way her throat had suddenly gone very dry. Cleared it. “Not at all.”

“You won’t regret this, ma’am. I promise.” Osgood looked back down, fiddling with the cuff of her lab coat. “I’ll talk to her. I’ll explain that what she said was completely inappropriate—“

“I’m not going to hold it against you,” Kate soothed before Osgood could work herself up into another attack. “Either of you. Heaven knows you’ve both been under incredible strain these past few weeks.” 

Osgood nodded, blinking rapidly. Was she about to cry? Kate tried to inject a teasing note into her voice to lighten the mood. “Although one thing did puzzle me…”

“Oh?” Osgood’s head popped up, as though she were a small animal on the lookout for predators. Her shoulders tensed as if expecting a blow.

It was the opposite of the reaction Kate had been going for, but she tried to soldier on, her voice carefully light-hearted, casual. “She seemed to assume that if we were in a relationship, I’d take you to a hotel for sex.” She paused, but Osgood, strangely enough, did not seem to be grasping the basic logical fallacy. “We both have flats.”

Osgood’s brow furrowed in confusion. It was adorable, and distracted Kate for a second from her response. “Well, we couldn’t go to my place. It’d be harder to block out the link to Petronella the closer we were. And you wouldn’t want to go to yours.”

Now it was Kate’s turn to frown. “Whyever not?”

“Because. You know.” Osgood shrugged. Her eyes fixed firmly on the cup of tea, as if it held all the answers in the universe. “You’d be ashamed of me.”

Kate felt a surge of emotion like a physical force inside of her, sorrow and anger and self-recrimination like a tidal wave. Through a throat that suddenly seemed constricted, she said, “I would _not.”_

Osgood’s face snapped up, disbelief written all over it. “But you don’t know if I’m human. And I’m a woman. And I’m not pretty—”

“You’re _Osgood,”_ Kate said firmly. “That is the only piece of information that matters in this equation.” She reached out impulsively, pressing her hands firmly around Osgood’s hands, not breaking eye contact for an instant. “And if I ever made you feel that anything else did, or that you didn’t, that was wrong, and I am so sorry. I am more sorry than you can imagine.”

Osgood’s fingers twitched under hers. Her throat worked briefly before she managed to whisper, “But...”

“And for the record,” Kate said before she could stop herself, “you are lovely.”

Osgood sucked in a ragged breath. “Kate—”

Osgood’s hands were so warm underneath Kate’s, the heat of the mug radiating out from under them. Osgood lips were slightly parted, and looked so soft. Kate suddenly realized that if she leaned forward a few more inches, they would be close enough to kiss.

“I need—time,” she said quickly. “To consider…all of this. Us.” Her fingers were stroking the back of Osgood’s hands. When had they started doing that? She made herself stop. “But I would—if you were amenable—I would like to see more of you. Later. At my flat.” 

A blush was creeping over the tops of Osgood’s cheeks like a sunrise. “For…”

“Coffee.” Kate squeezed her hand gently. “And perhaps we could see where it goes from there.”

Osgood smiled. “I’d like that.”


End file.
